Synchronization method of femtocell base station and femtocell base station using the same

Abstract

The exemplary embodiment of the present invention provides a method of synchronizing a femtocell base station securing time synchronization of a femtocell base station by allowing the femtocell base station to transmit a symbol to a terminal belonging to the femtocell by performing the time synchronization with a preamble signal when the femtocell base station receives the preamble signal from the macrocell base station in an orthogonal frequency division multiple access (OFDMA) communication system in which a femtocell is present in a macrocell.

What is claimed is: 
     
       1. A method of synchronizing a femtocell base station, comprising:
 allowing the femtocell base station to receive a preamble signal from a macrocell base station in an orthogonal frequency division multiple access (OFDMA) communication system in which a femtocell is present at any location within a macrocell; 
 performing a downlink synchronization of the femtocell with the received preamble signal, wherein the downlink synchronization includes matching downlink transmission start timing from the femtocell base station with the reception timing of a preamble signal having a first cyclic prefix (CP) from the macrocell base station; 
 allowing the femtocell base station to transmit a symbol having a second CP to a terminal belonging to the femtocell, 
 wherein the first CP and the second CP overlap within a guard interval of an OFDM symbol, and 
 wherein the downlink synchronization is performed at least when interference between the femtocell and the macrocell occurs. 
 
     
     
       2. The method of  claim 1 , wherein the femtocell uses the same frequency band as the macrocell. 
     
     
       3. The method of  claim 2 , wherein the femtocell performs transmission using subcarriers different from the macrocell. 
     
     
       4. The method of  claim 2 , wherein the femtocell performs transmission using the same subcarriers as the macrocell. 
     
     
       5. A femtocell base station present in a macrocell, comprising:
 an RF transceiver configured to receive a preamble signal from a macrocell base station in an orthogonal frequency division multiple access (OFDMA) communication system in which a femtocell is present at any location within a macrocell; 
 a synchronizer configured to perform downlink synchronization with the received preamble signal, wherein the downlink synchronization includes matching downlink transmission start timing from the femtocell base station with the reception timing of a preamble signal from the macrocell base station; 
 a ranging signal generator configured to generate a ranging signal and data to be transmitted to the macrocell base station; and 
 a frame generator configured to produce a frame using the to be transmitted data and the ranging signal, 
 wherein the synchronizer acquires uplink synchronization information from the macrocell base station according to the ranging signal to further perform the uplink synchronization to a terminal belonging to the femtocell by overlapping cyclic prefixes of signals transmitted from the at least one of the terminals within a guard interval of an OFDMA symbol by adjusting the uplink transmitting timing of the terminal to remove signal interference, and 
 wherein the synchronizer performs the downlink synchronization at least when interference between the femtocell and the macrocell occurs. 
 
     
     
       6. The femtocell base station of  claim 5 , further comprising:
 a demodulator configured to demodulate a symbol received from the macrocell base station and configured to transmit the demodulated symbol to a deframe generator; and 
 a detector configured to detect and a decoder configured to decode a data signal and a control signal output from the deframe generator. 
 
     
     
       7. The femtocell base station of  claim 5 , further comprising a coding and symbol mapping unit configured to transmit the to be transmitted data and the ranging signal output from the ranging signal generator to the frame generator. 
     
     
       8. The femtocell base station of  claim 7 , further comprising a modulator configured to modulate a frame output from the frame generator to configure a transmitting symbol.